WO1991008837A1 - Method for reducing the risk of back-corona in an electrostatic precipitator - Google Patents
Method for reducing the risk of back-corona in an electrostatic precipitator Download PDFInfo
- Publication number
- WO1991008837A1 WO1991008837A1 PCT/SE1990/000817 SE9000817W WO9108837A1 WO 1991008837 A1 WO1991008837 A1 WO 1991008837A1 SE 9000817 W SE9000817 W SE 9000817W WO 9108837 A1 WO9108837 A1 WO 9108837A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- gases
- precipitator
- water
- dust
- dust particles
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/01—Pretreatment of the gases prior to electrostatic precipitation
- B03C3/014—Addition of water; Heat exchange, e.g. by condensation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/01—Pretreatment of the gases prior to electrostatic precipitation
- B03C3/013—Conditioning by chemical additives, e.g. with SO3
Definitions
- the invention concerns a method for reducing the risk of back-corona in an electrostatic precipitator to which hot dust-containing gases are conducted via a gas supply duct and through which the gases are conducted for dust separation, wherein the gas temperature is reduced and the gas humidity increased by the addition to the gases, before these are conducted through the precipita ⁇ tor, of water which evaporates in the gases.
- electrostatic precipitators are made up of a plurality of successive precipitator units through which dust-containing gases are conducted for cleaning.
- Each of these units has an inner chamber which is divided into a plurality of parallel gas passages by means of a plurality of juxtaposed vertical curtains of earthed steel plates forming the collecting electrodes of the unit.
- a plurality of vertical wires, to which a negative voltage is applied, are arranged in each gas passage and form the discharge electrodes of each unit. Owing to corona discharges at the discharge electrodes, the gases are ionised in the electric field in the gas passages.
- the negative ions are attracted by the collecting electrodes and, when moving towards these, collide with dust particles in the gases, thereby charging the par ⁇ ticles which are separated from the gases by being attracted by the nearest collecting electrode, where they deposit and build up a layer of dust.
- dust separation efficiency increases with the voltage between the electrodes. The voltage should, however, not be too high, since that may cause flash- overs between the electrodes. Too high a current per unit area towards the collecting electrode may entail that the dust layer is charged faster than it is discharged to ⁇ wards the collecting electrode.
- each precipitator unit has a separately controllable current and/or voltage supply ⁇ ing circuit with associated control equipment, such that the current and/or voltage supply to each unit can be separately controlled.
- the current supply to the discharge electrodes of each unit is separately adjusted in such a manner that maximum dust separation efficiency is obtained.
- Another method for reducing the risk of back-corona consists in adding water to lower the temperature of the hot gases and increase their humidity, thereby reducing the resistivity of the dust.
- Such cooling of the hot gases by direct evaporation of water is usually carried out in a conditioning tower through which the gases are conducted before being conveyed to the electrostatic precipitator.
- Such towers are very large, since all the water injected therein must be evaporated before the gases leave.
- the object of the invention is to provide a simple, inexpensive and practicable method for reducing the risk of back-corona on the principle of reducing the gas temperature and increasing the gas humidity by adding water which evaporates in the gases.
- the larger dust particles are employed as carriers for the liquid, and are recycled.
- the liquid-carrying and recycled dust particles are dust particles separated in the first precipitator unit.
- the liquid suitably consists of water to which sodium has been added, preferably in the form of a sodium salt. In other applications, it suitably consists of water to which sulphur has been added, prefer- ably in the form av sulphuric acid.
- the drawing schematically illustrates a plant for cleaning dust-containing flue gases from a coal-fired boiler plant 1.
- a preheater 2 is adapted to transfer heat from the hot flue gases to combustion air which, through a duct 2a, is supplied to the plant 1 by means of a fan 3.
- the hot flue gases which may have a temperature of about 150°C, are conducted through a duct 4 to an electro ⁇ static precipitator 5 made up of three successive precipi ⁇ tator units 5a, 5b, 5c through which the gases are con- ducted for cleaning.
- the thus cleaned flue gases are conducted through a duct 6 to a flue gas fan 7 which conveys the gases through a duct 8 to a chimney 9 for emission into the atmosphere.
- Each of the successive precipitator units 5a, 5b, 5c is of conventional type and has an inner chamber divided into a plurality of parallel gas passages by means of a plurality of juxtaposed vertical curtains of earthed steel plates, i.e. collecting electrodes.
- a plurality of vertical wires, i.e. discharge electrodes, connected to a voltage of about -50 kV, are arranged in each gas passage.
- the flue gases are ionised in the electric field in these passages.
- the negative ions are attracted by the collect- ing electrodes and collide, when moving towards these, with dust particles in the flue gases, thereby charging these particles, which are separated from the gases by being attracted by the nearest collecting electrode, where they are deposited.
- the dust particles deposited on the collecting electrodes build up a layer of dust which at regular intervals are dislodged. Then, the dust particles drop into the collecting hopper 10a, 10b and 10c of each precipitator unit.
- the dust particles collected by the hopper 10b of the second unit 5b being smaller than those collected by the hopper 10a of the first unit 5a, as well as the dust particles collected by the hopper 10c of the third unit 5c, being smaller than those collected in the hopper 10b of the second unit 5b, are removed from the hoppers 10b and 10c by conveyor means lib and lie, shown only schematically.
- Some of the dust particles collected by the hopper 10a of the first unit 5a are recycled in the system via a device 12 in a manner described in more detail below.
- the remaining dust particles in the hopper 10a of the first unit 5a are removed by a conveyor means Ila (shown only schematically) and the conveyor means lib and lie.
- the device 12 shown most schematically comprises a container 13 for intermediate storage of the dust par- tides which are to be recycled.
- a valve device or gate- type feeder 14 is arranged below the container 13 and adapted to feed the dust particles to a screw conveyor 15, which transports the dust particles to a conduit 16 ending in the flue gas duct 4.
- a strong air current (indicated by arrows) is blown through the conduit 16.
- the dust particles are showered with water.
- the water is supplied to the screw conveyor 15 through a connection 17, and conveyed to the conduit 16 jointly with the dust par ⁇ ticles.
- the dust particles serving as carriers for the added water are blown into the flue gas duct 4.
- the water evaporates in the flue gases, thus reducing the gas tem ⁇ perature and increasing the gas humidity.
- the amount of water admitted through the connection 17 is porportioned so as to bring about the desired reduction in temperature of the flue gases.
- the water may in some applications contain sodium, added in the form of a sodium salt, or sulphur, added in the form of sulphuric acid.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE69025625T DE69025625T2 (en) | 1989-12-11 | 1990-12-10 | METHOD FOR PREVENTING BACK SPRAYING IN AN ELECTRIC SEPARATOR |
EP91900972A EP0505426B1 (en) | 1989-12-11 | 1990-12-10 | Method for reducing the risk of back-corona in an electrostatic precipitator |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE8904154A SE466581B (en) | 1989-12-11 | 1989-12-11 | SET TO REDUCE RISK BEFORE ETERNAL RADIATION IN AN ELECTROSTATIC DUST DISPENSER |
SE8904154-5 | 1989-12-11 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1991008837A1 true WO1991008837A1 (en) | 1991-06-27 |
Family
ID=20377727
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SE1990/000817 WO1991008837A1 (en) | 1989-12-11 | 1990-12-10 | Method for reducing the risk of back-corona in an electrostatic precipitator |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP0505426B1 (en) |
AT (1) | ATE134533T1 (en) |
AU (1) | AU635807B2 (en) |
CA (1) | CA2070661A1 (en) |
DE (1) | DE69025625T2 (en) |
ES (1) | ES2086527T3 (en) |
SE (1) | SE466581B (en) |
WO (1) | WO1991008837A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1967275A1 (en) | 2007-03-05 | 2008-09-10 | Alstom Technology Ltd | A method and a control system for controlling the operation of a last field of an electrostatic precipitator |
EP1967277A1 (en) * | 2007-03-05 | 2008-09-10 | Alstom Technology Ltd | A method of controlling the order of rapping the collecting electrode plates of an ESP |
EP1967276A1 (en) | 2007-03-05 | 2008-09-10 | Alstom Technology Ltd | A method of estimating the dust load of an ESP, and a method and a device of controlling the rapping of an ESP |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3512340A (en) * | 1962-05-19 | 1970-05-19 | Kloeckner Humboldt Deutz Ag | Method and apparatus for cooling and humidifying a hot gas flow |
US4533364A (en) * | 1983-02-01 | 1985-08-06 | Electric Power Research Institute, Inc. | Method for flue gas conditioning with the decomposition products of ammonium sulfate or ammonium bisulfate |
-
1989
- 1989-12-11 SE SE8904154A patent/SE466581B/en unknown
-
1990
- 1990-12-10 ES ES91900972T patent/ES2086527T3/en not_active Expired - Lifetime
- 1990-12-10 AT AT91900972T patent/ATE134533T1/en not_active IP Right Cessation
- 1990-12-10 AU AU69599/91A patent/AU635807B2/en not_active Ceased
- 1990-12-10 DE DE69025625T patent/DE69025625T2/en not_active Expired - Fee Related
- 1990-12-10 WO PCT/SE1990/000817 patent/WO1991008837A1/en active IP Right Grant
- 1990-12-10 EP EP91900972A patent/EP0505426B1/en not_active Expired - Lifetime
- 1990-12-10 CA CA002070661A patent/CA2070661A1/en not_active Abandoned
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3512340A (en) * | 1962-05-19 | 1970-05-19 | Kloeckner Humboldt Deutz Ag | Method and apparatus for cooling and humidifying a hot gas flow |
US4533364A (en) * | 1983-02-01 | 1985-08-06 | Electric Power Research Institute, Inc. | Method for flue gas conditioning with the decomposition products of ammonium sulfate or ammonium bisulfate |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1967275A1 (en) | 2007-03-05 | 2008-09-10 | Alstom Technology Ltd | A method and a control system for controlling the operation of a last field of an electrostatic precipitator |
EP1967277A1 (en) * | 2007-03-05 | 2008-09-10 | Alstom Technology Ltd | A method of controlling the order of rapping the collecting electrode plates of an ESP |
EP1967276A1 (en) | 2007-03-05 | 2008-09-10 | Alstom Technology Ltd | A method of estimating the dust load of an ESP, and a method and a device of controlling the rapping of an ESP |
EP2338603A1 (en) | 2007-03-05 | 2011-06-29 | Alstom Technology Ltd | A method and a control system for controlling the operation of a last field of an electrostatic precipitator |
US8268040B2 (en) | 2007-03-05 | 2012-09-18 | Alstom Technology Ltd | Method of controlling the order of rapping the collecting electrode plates of an ESP |
US8328902B2 (en) | 2007-03-05 | 2012-12-11 | Alstom Technology Ltd | Method of estimating the dust load of an ESP, and a method and a device of controlling the rapping of an ESP |
Also Published As
Publication number | Publication date |
---|---|
SE8904154D0 (en) | 1989-12-11 |
SE466581B (en) | 1992-03-09 |
AU6959991A (en) | 1991-07-18 |
EP0505426A1 (en) | 1992-09-30 |
ATE134533T1 (en) | 1996-03-15 |
AU635807B2 (en) | 1993-04-01 |
EP0505426B1 (en) | 1996-02-28 |
DE69025625D1 (en) | 1996-04-04 |
SE8904154L (en) | 1991-06-12 |
ES2086527T3 (en) | 1996-07-01 |
CA2070661A1 (en) | 1991-06-12 |
DE69025625T2 (en) | 1996-08-01 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4072477A (en) | Electrostatic precipitation process | |
US4349359A (en) | Electrostatic precipitator apparatus having an improved ion generating means | |
US4435190A (en) | Method for separating particles in suspension in a gas | |
US3807137A (en) | Electrostatic gas-scrubber and method | |
US4162144A (en) | Method and apparatus for treating electrically charged airborne particles | |
EP0775527A1 (en) | Venturi insulator for use in an electrostatic precipitator | |
EP2868384B1 (en) | Wet electric dust-collecting device and exhaust gas treatment method | |
US3365858A (en) | Combined heat interchanger and electrostatic precipitator | |
AU635807B2 (en) | Method for reducing the risk of back-corona in an electrostatic precipitator | |
CA1042366A (en) | Electrostatic scrubbers involving charged liquid sprays and oppositely charged dust particles | |
US4244709A (en) | High intensity ionization-electrostatic precipitation system for particle removal and method of operation | |
US4619670A (en) | Apparatus for dielectrophoretically enhanced particle collection | |
EP1361927A1 (en) | Electrostatic dust separator with integrated filter tubing | |
US4236900A (en) | Electrostatic precipitator apparatus having an improved ion generating means | |
US7261764B1 (en) | System and method for spatially-selective particulate deposition and enhanced deposition efficiency | |
US2764254A (en) | Electrostatic precipitator circuits | |
US4238203A (en) | Method of enhancing the effectiveness of electrostatic precipitators used with gas streams formed from burning fuel | |
JPS6028545B2 (en) | Method and device for separating fine particles in gas | |
US2792316A (en) | Method for cleaning gas-swept heating surfaces | |
Dalmon | Electrostatic precipitators for large power station boilers | |
CN215744118U (en) | Star-shaped electrode for electrostatic dust collection of belt type conveying equipment and electrostatic dust collection system | |
US2726730A (en) | Gas cleaning device | |
SU988341A1 (en) | Apparatus for charging and depositing dust particles | |
RU2181466C1 (en) | Ionic air-cleaning fan | |
CN113000215A (en) | Star-shaped electrode for electrostatic dust collection of belt type conveying equipment and electrostatic dust collection system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AT AU BB BG BR CA CH DE DK ES FI GB GR HU JP KP KR LK LU MC MG MW NL NO RO SD SE SU US |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE BF BJ CF CG CH CM DE DK ES FR GA GB GR IT LU ML MR NL SE SN TD TG |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1991900972 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2070661 Country of ref document: CA |
|
REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
WWP | Wipo information: published in national office |
Ref document number: 1991900972 Country of ref document: EP |
|
WWG | Wipo information: grant in national office |
Ref document number: 1991900972 Country of ref document: EP |